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Tuesday, August 18, 2009

No Increased Risk of Kidney Stones from Extra Calcium

I always advise people who avoid dairy products to think about calcium supplements. Sure, the militant vegans are very loud and insistent that you can get a full allowance of calcium from non-dairy sources and that's technically true. The reality is that very few people eat that diet. Check out this government listing of nondairy calcium sources at Appendix B-4. It's neither large nor varied.

Therefore a calcium pill with added vitamin D to help absorption is normally a must for the average person. The type of calcium doesn't matter, unless you have difficulties manufacturing stomach acid. Some of the elderly and people on certain medication have this problem. For them the standard calcium carbonate is not the right option. Try calcium citrate instead.

One more problem. Americans are not a people who aim for "just right". When they don't under-do they overdo. Some people will have calcium from their food (some dairy as well as nondairy) plus calcium supplements. And that raises a risk of a calcium overconsumption.

Remember, the risk is being raised only from essentially zero to a tiny bit more than zero. The kidneys will strain out any slight excess of calcium and excrete it in the urine. This raises yet another issue. Kidney stones. Kidney stones typically are calcium precipitated out in the form of calcium oxalate or calcium phosphate.

Nobody wants the pain of passing a kidney stone. So do calcium supplements increase your risk of kidney stones?

Linda G. Fugate wondered about this on

The answer from the medical literature surprised me. In a study of men under the age of 60, the risk of kidney stones decreased with increasing calcium in the diet. This is backwards from what we would expect, and the authors of the paper have no explanation. For men over age 60, the amount of calcium in the diet had no effect on formation of kidney stones. I have not yet found comparable data for women. The main risk for kidney stones in women appears to be weight. See

Researchers at the University of California report that potassium and bicarbonate ions tend to keep calcium in the bones, while sodium and chloride ions tend to increase calcium in the urine and promote the formation of kidney stones. Bicarbonate ions are formed from the metabolism of organic compounds, mainly citrate, found in fruits and vegetables. Potassium is also abundant in fruits and vegetables (but not grains).

According to these researchers, both potassium and bicarbonate have a positive effect on the kidney's ability to regulate calcium excretion. Bicarbonate also prevents calcium loss from the bones by balancing the pH (a measure of acidity or alkalinity) of the blood and tissue fluids. Too much sodium, on the other hand, interferes with the kidney's regulation of calcium.

So I'm continuing the calcium supplements and eating plenty of vegetables.

Good news. Keep adding calcium to your diet. Try to avoid overconsumption, but don't worry too much if you can't keep your dosages straight. Bookmark this. That's probably the first and last time I'll say anything so radical.

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